Degree Type

Dissertation

Date of Award

1982

Degree Name

Doctor of Philosophy

Department

Animal Science

Abstract

Gluconeogenic and ketogenic capacities of liver slices as well as metabolite concentrations in plasma and liver were examined in five dairy cows before and after an experimental lactation ketosis, and in four dairy steers treated with phlorizin (P) and/or 1,3-butanediol (BD). Liver biopsies were performed in lactating cows once before parturition and four times within 50 days following parturition. All cows were restricted approximately 15% from ad libitum feed consumption at 14 days postpartum. Four cows became ketotic (average 36 days postpartum) and were characterized during ketosis, compared to early lactation, by: a 66 (+OR-) 6% decrease in propionate, lactate, ALA, ASP, and GLU conversion to glucose; a 47 (+OR-) 6% decrease in the same substrates oxidized to carbon dioxide: and a 70% decrease in (beta)-hydroxybutyrate (BHBA) synthesis when incubated with butyrate. Also, ketotic cows lost body weight at a rate of 3.1 kg/day, and during ketosis, compared to prepartum, showed; a 10 to 15 fold increase in plasma and hepatic ketone bodies (KB), a 10 fold increase in hepatic triglyceride, and a 90% decrease in hepatic glycogen. Much less drastic changes were noted for the nonketotic cow;Liver biopsies were performed on the four steers at the end of each period of a 4 x 4 Latin square trial, and following 6 days of feed restriction in three of the four steers after completion of the Latin square trial. Treatments for the Latin square were: (C) is control, hay plus corn ration; (BD) is C + butanediol added to the ration; (P) is C + twice daily subcutaneous injections of 1 g of phlorizin; and (PBD) is C + P + BD. Glucose production (nmoles substrate converted to glucose/100 mg liver x 1 h) from propionate, lactate, and ASP when fed C was 974, 334, and 101, respectively. Feeding BD increased plasma and hepatic BHBA, and depressed glucose production from propionate (22%) and lactate (35%) compared to C. Phlorizin (P or PBD) or restricted feeding increased glucose production from propionate (32 to 74%), lactate (55 to 160%), and ASP (32-41%). KB (10 mM) plus 1 mM stearate added in vitro, completely negated the increased glucose production due to feed restriction. KB suppress hepatic metabolism, which may be an important contributor to ketosis development.

DOI

https://doi.org/10.31274/rtd-180813-6035

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Scott E. Mills

Language

en

Proquest ID

AAI8221209

File Format

application/pdf

File Size

230 pages

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